Quattro Adventure

Level warps are certain spots in certain levels that will send you directly to the next level without the need to collect any more boomerangs or reach the regular level exit. You will not receive any points for unobtained boomerangs or time left on the clock if you use them, however.

Shark City: Climb up and jump above the hill on the left.
Shark Fin Creek: Just above the first shark pool; it's easiest to jump onto the center of the crumbling platform and fall straight in.
Tower of the Forgotten Knights: Climb to the top floor, then jump off the far left edge.
The Secret Chamber: At the start, carefully jump over the chair to your left, then move further left and jump again if you haven't already hit the warp.
Backstab Alley: Jump onto the very first platform in front of you at the start, then jump up to the left.
Hopping Mad Halt: On the bottom floor, in between the center and right edge of the screen, do a small jump.

Just after the Codemasters logo, immediately press A, B, Select, and Start before the title screen can appear to view the credits.

To activate the CHR RAM "Smiley Test" easter egg for this game, you will need to power on the NES/Famicom console while holding Up, Down, Left, Right, B, Select, and Start. Note, however, that it is not normally possible to hold all four D-Pad buttons without specially modified controllers; standard NES/Famicom controllers will not work.

At the title screen for this game, hold Left and A, then press Start.

At the title screen, hold Up, A, and B on Controller 1 and Up, Right, A, and Select on Controller 2, then press Start. (Those wishing to play with Controller 2 must swap the buttons: Up+A+B for Controller 2, and Up+Right+A+Select for Controller.) This code will make you invulnerable and you'll also start from the Island in the Sky area.

At the title screen, if you begin gameplay by pressing Start on Controller 2, you will be able to play with Controller 2.

Go underwater (Right of the start) and find the platform on the left side of the sunken ship. Jump onto the platform and move to the right side. Pressing B will allow you to view the credits.